Transistors are used to form a variety of electronic devices. A popular type of transistor is a complementary metal-oxide-semiconductor (CMOS) transistor because of a relatively low power consumption, speed and ease of manufacture. CMOS transistors are used in devices such as a CMOS image sensor (CIS). CIS are susceptible to random telegraph signal (RTS) noise and flicker noise, which reduces the sensitivity of the CIS.
A source of RTS noise and flicker noise in CIS is trapped charge carriers at an interface between a channel and an isolation feature. Charge carriers become trapped at the interface of the channel and the isolation feature during periods of conductivity for the transistor. In some instances, the trapped charge carriers are embedded in a surface of the isolation feature or in a surface of a gate dielectric layer of the transistor. As these trapped charge carriers break free of the isolation feature or gate dielectric layer, a current through the channel experiences unpredictable increases which results in noise in the output of the transistor.